This invention relates generally to refrigeration apparatus and, more particularly, to a refrigeration unit for use in cooling the interior of a portable refrigerator chest.
Portable chests having refrigerated interior storage areas are useful in many applications such, for example, as in food containers, medical supply storage containers, etc. In the past, such a chest often merely included a thermally insulated ice (or "dry ice") containing box. These chests are subject to obvious disadvantages, including the weight and bulk of the ice, not to mention the need to periodically replenish the ice supply which melts (or vaporizes) over a period of time.
Relatively recently, attempts have been made to provide iceless portable refrigerator chests. Generally, these portable refrigerator units include single cycle refrigerant systems (i.e., no compressor is provided) wherein stored liquid refrigerant is directed through an evaporator positioned within the refrigerator compartment where the refrigerant evaporates and thus reduces the temperature within the container. Although these units are more desirable than the ice charged boxes, frequently, the liquid refrigerant fails to completely evaporate which reduces the efficienty of the device. Incomplete evaporation also creates a safety hazard, since excess liquid refrigerant might escape from the system and come into contact with the skin causing severe "freeze burns". Another disadvantage of both portable "iceless" and ice charged refrigerator chests is that the temperature within the chest has not been controllable to a suitable degree, but rather is dependent upon the quantity of ice or charge of refrigerant within the chest.